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R.R. Krueger, I.L. Thornton, T.J. van den Berg; Rainbow Glare as Optical Side Effect of IntraLASIK . Invest. Ophthalmol. Vis. Sci. 2006;47(13):4330.
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© ARVO (1962-2015); The Authors (2016-present)
To report on a new optical side effect associated with the IntraLASIK procedure.
A retrospective review was performed on 571 eyes of 301 patients treated with IntraLASIK over a period from June 2004 to August 2005. The eyes are divided into two groups: Group I represents 403 eyes (215 patients) treated with the IntraLase I laser at a spot separation of 9 to 11 um, line separation of 9 um and raster energies varying from 1.3 –2.6 uJ. Group II represent 168 eyes (86 patients) treated with the IntraLase II laser at a spot and line separation of 9 to 10 um and raster energy of 1.3 uJ. Pre and post–op refraction, pupillometry, pachymetry, visual acuity, wavefront aberrations, and report of symptoms were recorded. The spatial extent of the rainbow spectral pattern was drawn for calculation of the size of the grating pattern causing the light scatter.
In Group I, 164 of the 215 patients (76.3%) were successfully contacted to specifically ask whether they experienced symptoms of halos or starburst at night and/or rainbow colors around lights. 31 patients in 58 eyes reported symptoms of spectral starburst around lights (rainbow glare) for an incidence of 18.9%. In Group II, 0 patients reported similar symptoms. The spectral pattern most closely represented 6–12 radiating lines of rainbow colored light, which was noted immediately after surgery and in some eyes diminished over time. The spatial extent of the color pattern ranged from 2.5 to 4.5 degrees of visual angle around point light sources (ie. radiating bands extending ∼25mm (blue) to ∼34mm (yellow) to ∼40 mm (red) around a centrally placed light, when drawn on paper held ∼55 cm from the patient’s eye). This could be calculated using grating formulas to correspond to a ∼9 um sized periodicity pattern within the corneal interface.
Light scattering from the back surface of the IntraLASIK flap causes a constructive interference, creating a spectral pattern in a significant percentage (∼20%) of Group I eyes. The angular extent of the color pattern can be calculated to correspond to a grating size that matches the approximate raster spot separation and pattern of IntraLase pulsing. The spectral pattern was not observed in Group II eyes where a tighter focus minimizes the light scattering phenomenon. Variance in the quality of focusing optics impacts the precision of spot placement and interface uniformity in IntraLase flap creation, which when optimized eliminates the possibility of rainbow glare as an optical side effect.
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